The Two Diurnal Modes of Tropical Upward Motion
The Two Diurnal Modes of Tropical Upward Motion
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DOI：
10.1029/2018gl081806
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发表时间：
2019-03
影响因子：
5.2
通讯作者：
J. Ruppert;D. Klocke
中科院分区：
文献类型：
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作者：
J. Ruppert;D. Klocke
这项研究描述了一种新的机制，该机制管理着热带海洋重降雨带的纵向运动，例如在此类区域中的热带收敛带。下午，这个径向驱动器促进了一个下午的砧云，表明昼夜云相反的发生在夜间：虽然降雨在夜间早晨表现出主要的峰值，但边界层扎根于向上的运动，而与此峰的潜在升温被迫更底部，因为夜间在夜间的辐射冷却在白天有利于层状的高度加热模式，并抑制了这些昼夜循环标志。有组织的深度转换尺度，最终可能会影响日常平均辐射预算。
This study describes a new mechanism governing the diurnal variation of vertical motion in tropical oceanic heavy rainfall zones, such as the intertropical convergence zone. In such regions, the diurnal heating of widespread anvil clouds due to shortwave radiative absorption enhances upward motion in these upper layers in the afternoon. This radiatively driven ascent promotes an afternoon maximum of anvil clouds, indicating a diurnal cloud‐radiative feedback. The opposite occurs at nighttime: While rainfall exhibits a dominant peak at night‐early morning, the boundary layer rooted upward motion and latent heating tied to this peak are forced to be more bottom heavy by the nighttime anomalous radiative cooling at upper levels. This mechanism therefore favors the stratiform top‐heavy heating mode during daytime and suppresses it nocturnally. These diurnal circulation signatures arise from microphysical‐radiative feedbacks that manifest on the scales of organized deep convection, which may ultimately impact the daily mean radiation budget.